Gastrointestinal effects and energy value of polydextrose in healthy nonobese men

Gastrointestinal Effects and Tolerance of Nondigestible Carbohydrate Consumption

Nondigestible carbohydrates (NDCs) are food components, including nonstarch polysaccharides and resistant starches. Many NDCs are classified as dietary fibers by the US FDA. Because of their beneficial effects on human health and product development, NDCs are widely used in the food supply. Although there are dietary intake recommendations for total dietary fiber, there are no such recommendations for individual NDCs. NDCs are heterogeneous in their chemical composition and physicochemical properties-characteristics that contribute to their tolerable intake levels. Guidance on tolerable intake levels of different NDCs is needed because overconsumption can lead to undesirable gastrointestinal side effects, further widening the gap between actual and suggested fiber intake levels. In this review, we synthesize the literature on gastrointestinal effects of NDCs that the FDA accepts as dietary fibers (β-glucan, pectin, arabinoxylan, guar gum, alginate, psyllium husk, inulin, fructooligosaccharides and oligofructose, galactooligosaccharides, polydextrose, cellulose, soy fiber, resistant maltodextrin/dextrin) and present tolerable intake dose recommendations for their consumption. We summarized the findings from 103 clinical trials in adults without gastrointestinal disease who reported gastrointestinal effects, including tolerance (e.g., bloating, flatulence, borborygmi/rumbling) and function (e.g., transit time, stool frequency, stool consistency). These studies provided doses ranging from 0.75-160 g/d and lasted for durations ranging from a single-meal tolerance test to 28 wk. Tolerance was NDC specific; thus, recommendations ranged from 3.75 g/d for alginate to 25 g/d for soy fiber. Future studies should address gaps in the literature by testing a wider range of NDC doses and consumption forms (solid compared with liquid). Furthermore, future investigations should also adopt a standard protocol to examine tolerance and functional outcomes across studies consistently.

Re-evaluation of polydextrose (E 1200) as a food additive

This opinion deals with the re-evaluation of polydextrose (E 1200) when used as a food additive. The Panel followed the conceptual framework for the risk assessment of certain additives and considered that: adequate exposure estimates were available; the margin of safety (MOS)/margin of exposure (MOE) for arsenic was between 0.5-14 and 8.5 for lead; the exhaustions of the tolerable weekly intake (TWI) for cadmium would be 165%, 10% for mercury, whereas the exhaustion of the tolerable daily intake (TDI) for nickel would be 9%; the absorption is limited and part of polydextrose is fermented in the large intestine into short-chain fatty acids (SCFA); adequate toxicity data were available; there is no concern with respect to genotoxicity; no adverse effects were reported in subchronic studies in rats, dogs or monkeys nor in chronic or carcinogenicity studies in mice and rats at the highest doses tested of up 12,500 mg/kg body weight (bw) per day and 15,000 mg/kg bw per day, respectively; the nephrocalcinosis in dogs given high doses of polydextrose was considered to be a treatment-related but a secondary effect related to diarrhoea, and hence not relevant for the risk assessment; no adverse effects were reported in reproductive or developmental toxicity studies in rats administered up to 10,000 mg polydextrose/kg bw per day, or in a developmental toxicity study in rabbits up to 1,818 mg/kg bw per day (the highest dose tested). Therefore, the Panel concluded that there is no need for numerical acceptable daily intake (ADI) for polydextrose (E 1200), and that there is no safety concern for the reported uses and use levels of polydextrose as a food additive. The Panel recommended that European Commission considers to lower the maximum limit for lead and to introduce limits for arsenic, cadmium and mercury in the EU specifications for polydextrose (E 1200), and to verify that polydextrose-N as a food additive (E 1200) is no longer marketed in the EU.

Influência da incorporação de polidextrose como substituto de gordura na qualidade de pão de queijo

Resumo Um dos grandes desafios do desenvolvimento de produtos com baixos teores de gordura é manter suas características sensoriais. A polidextrose pode ser utilizada como um substituto de gordura, sem causar grandes alterações no produto final. O objetivo deste estudo foi avaliar as características físico-químicas, propriedades nutricionais e investigar o potencial de aceitação de pães de queijo formulados com polidextrose. Foram elaboradas 4 formulações: formulação 1 (sem substituição de óleo por polidextrose); formulações 2, 3 e 4 (contendo diferentes concentrações de substituição de óleo e polidextrose). Participaram da avaliação sensorial 100 provadores não treinados, de 18 a 62 anos. Nas análises físico-químicas foram determinados os teores de água, cinzas, proteínas, lipídeos, textura, volume específico e cor, sendo realizado cálculo teórico para quantificação de carboidratos (por diferença) e fibras. Os resultados demonstraram que nos atributos avaliados as formulações obtiveram aceitabilidade superior a 70%, exceto o atributo intenção de compra da formulação padrão. Foi observado que o desenvolvimento de formulações contendo 4% de polidextrose apresentaram textura semelhante à formulação padrão. Assim, a adição de polidextrose em pães de queijo permitiu a obtenção de produtos com menores teores de lipídeos, maior teor de fibras, boa aceitação sensorial e características tecnológicas semelhantes ao padrão, indicando seu potencial de comercialização.

Efficacy of Polydextrose Supplementation on Colonic Transit Time, Bowel Movements, and Gastrointestinal Symptoms in Adults: A Double-Blind, Randomized, Placebo-Controlled Trial

The addition of fiber is one of the most important dietary means to relieve constipation through lifestyle modification. Polydextrose (PDX) has been reported in several studies to increase fecal bulk, soften stools, and increase the number of defecations. However, there are few studies on the effect of PDX on colonic transit time (CTT). Therefore, the aim of this study was to demonstrate the effect of PDX on CTT and other aspects of gastrointestinal function during two weeks (Day 1 to Day 14), preceded by a 2-week run-in period (Day -14 to Day -1). A total of 192 adults who were diagnosed with functional constipation per Rome III criteria were recruited for the study. Participants were randomized equally into 4 groups (12 g, 8 g, or 4 g of PDX or placebo per day). The primary endpoint was CTT, assessed using radio-opaque markers and abdominal X-rays on Day 0, the baseline; and Day 15, the end of the intervention. Secondary outcomes that were measured using inventories were the patient assessment of constipation symptoms and quality of life, bowel function index, relief of constipation, bowel movement frequency (BMF), stool consistency, degree of straining, and proportion of bowel movements. Ancillary parameters and harms were also evaluated. The recruited population was not sufficiently constipated (e.g., baseline values for CTT and BMF of 42 h and 8.7 BMF/week, respectively). Despite this limitation, our results demonstrated an increased number of bowel movements when supplemented with PDX at a dosage of 12 g per day for 2 weeks. This dosage also consistently improved the secondary outcomes that were measured using inventories at Day 15, compared with the baseline. No serious or significant adverse events were reported during the study.

Unravelling the Effects of Soluble Dietary Fibre Supplementation on Energy Intake and Perceived Satiety in Healthy Adults: Evidence from Systematic Review and Meta-Analysis of Randomised-Controlled Trials

Consumption of soluble dietary fibre is recommended as part of a healthy diet. Evidence has shown that soluble dietary fibre slows gastric emptying, increases perceived satiety and plays a significant role in appetite regulation. This systematic review examined the effects of soluble dietary fibre using randomised-controlled trials (RCTs). Three different electronic databases were used, namely PubMed, Scopus® and the Cochrane Central Register of Controlled Trials (CENTRAL). Effect size (Cohen's d) was calculated based on the intergroup mean difference and standard deviation (SD) followed by Cochran's Q and I² determination. The effect size was statistically pooled in the meta-analyses and presented as a forest plot. The risk of bias was high for each study as assessed using the Jadad scale. Meta-analysis of statistically pooled data for guar gum showed a sizeable effect on post-meal energy intake, followed by β-glucan, alginate, polydextrose and pectin, with pooled effect sizes of -0.90, -0.44, -0.42, -0.36 and -0.26, respectively. Guar gum (5 g) effectively reduced energy intake when prepared in milk beverages compared with control milk (p < 0.001). Alginate, when prepared in liquid (5 g) or solid (9 g) meals, effectively reduced energy intake compared with control (p < 0.001). A high dose of polydextrose (25 g) prepared in liquid meal form significantly reduced energy intake (p = 0.01). This study suggests that soluble fibres are not all created equal. Further interventional studies are needed to determine whether combinations of these soluble fibres might have greater effects than individual fibres per se.

Short-Term Daily Intake of Polydextrose Fiber Does Not Shorten Intestinal Transit Time in Constipated Adults: A Randomized Controlled Trial

Chronic constipation (CC) remains a common gastrointestinal (GI) disorder that conveys a substantial healthcare burden. Expert guidelines recommend increasing fiber intake, yet the clinical evidence to support this needs strengthening for specific fibers. The aim was to evaluate changes in intestinal transit time and GI symptoms in CC patients who consumed polydextrose. In a randomized, double-blind, placebo-controlled trial, 128 adults with CC received 8 g or 12 g polydextrose, or placebo, daily for 4 weeks. Transit time, as primary outcome, was assessed by radiopaque marker distribution after 2-weeks intervention. Bowel habits, GI symptoms and quality of life (QOL) were assessed by questionnaire, including the Patient-Assessment of Constipation (PAC) Symptoms (SYM), and PAC-QOL. Following 2-weeks intervention, no reduction was seen in transit time in any group and following 2- or 4-weeks intervention, no improvements were seen in stool frequency or consistency in any group. After 2-weeks intervention with 8 g/day polydextrose an improvement was seen in the PAC-SYM rectal score (p = 0.041). After 4-weeks intervention both rectal (p = 0.049) and stool (p = 0.029) scores improved while improvement in the QOL satisfaction score did not reach significance (p = 0.071). Overall, the results suggest that 2-weeks consumption of 8 or 12 g/day polydextrose does not significantly improve physiological measures of gut function in CC adults. Longer term consumption may improve clinical measures, but further studies will be required to substantiate this.

Fermented Fiber Supplements Are No Better Than Placebo for a Laxative Effect

BACKGROUND

Misconceptions about the effects of dietary fiber and 'functional' fiber on stool parameters and constipation persist in the literature.

METHODS

A comprehensive literature review was conducted with the use of the Scopus and PubMed scientific databases to identify and objectively assess well-controlled clinical studies that evaluated the effects of fiber on stool parameters and constipation.

RESULTS

The totality of well-controlled randomized clinical studies show that, to exert a laxative effect, fiber must: (1) resist fermentation to remain intact throughout the large bowel and present in stool, and (2) significantly increase stool water content and stool output, resulting in soft/bulky/easy-to-pass stools. Poorly fermented insoluble fiber (e.g., wheat bran) remains as discreet particles which can mechanically irritate the gut mucosa, stimulating water & mucous secretion if the particles are sufficiently large/coarse. For soluble fibers, some have no effect on viscosity (e.g., inulin, wheat dextrin) while others form high viscosity gels (e.g., β-glucan, psyllium). If the soluble fiber is readily fermented, whether non-viscous or gel-forming, it has no effect on stool output or stool water content, and has no laxative effect. In contrast, a non-fermented, gel-forming soluble fiber (e.g., psyllium) retains its gelled nature and high water-holding capacity throughout the large bowel, resulting in soft/bulky/easy-to-pass stools.

CONCLUSION

When considering a recommendation for a fiber supplement regimen to treat and/or prevent constipation, it is important to consider which fibers have the physical characteristics to exert a laxative effect, and which fiber supplements have rigorous clinical evidence of a significant benefit in patients with constipation.

Effect of Polydextrose Intake on Constipation in Japanese Dialysis Patients: A Triple-Blind, Randomized, Controlled Trial

The objective of the present study was to evaluate bowel habits induced by ingestion of 10 g polydextrose (PDX) fed to Japanese hemodialysis (HD) patients. This was a randomized, placebo-controlled, triple-blind, parallel-group controlled, 8-wk study. A total of 50 HD outpatients capable of self-management (51-79 y of age) were recruited at H Clinic, Japan. Inclusion criteria for participation in the study were ingestion of one or more laxative tablets for more than 3 mo and having received HD for more than 6 mo. The participants were randomly assigned to 2 groups: A (0 g polydextrose/d; control), B (10 g polydextrose/d; PDX). The primary outcome measure was stool frequency. Secondary outcomes were stool consistency, abdominal pain, intestinal bloating and clinical biochemistry indexes. PDX had no significant effect on blood biochemistry indexes. The PDX group showed significant improvements in bowel function (stool frequency increased from 3.0 times per week to 7.5 times per week) and reported no laxation problems (abdominal distention, cramps, and diarrhea) (p<0.01). Regular consumption of the PDX products increased dietary fiber intake to recommended levels and improved bowel habits.

Evaluation of the relative available energy of several dietary fiber preparations using breath hydrogen evolution in healthy humans

A standardized simple, indirect method for assessing the relative energy of dietary fiber carbohydrates is not yet established. There is a need for a standardized in vivo assay. The objective of the present study was to evaluate the relative available energy (RAE) for 9 major dietary fiber materials (DFMs) based on fermentability from breath hydrogen excretion (BHE) in subjects. Fructooligosaccharide (FOS) was used as a reference. The study was conducted using a within-subject, repeated measures design and approved by the Ethical Committee of University of Nagasaki. After DFM ingestion, end-expiratory gas (750-mL) was collected at 1-h intervals for 8 h, as well as at 2-h intervals between 8 h and 14 h, and 30 min after waking up and 24 h after DFM ingestion. Breath hydrogen concentration was assessed with a gas chromatograph. The RAE of DFMs tested was evaluated based on the area under the curve (AUC) of BHE of FOS. Based on the ratio of AUC for 8 h, the RAE of polydextrose, partially hydrolysed guar gum, resistant maltodextrin and partially hydrolysed alginate was 1 kcal/g, and that of glucomannan, heat-moisture treatment and high-amylose cornstarch and cellulose was 0 kcal/g, while the RAE of all tested DEMs including cellulose and glucomannan was 1 kcal/g in the calculation based on AUCs for 14 h and 24 h in subjects. We suggest that a breath hydrogen collection period of 14 h or more could be used to measure RAE for a range of fiber preparations in vivo.

Effects of polydextrose on different levels of energy intake. A systematic review and meta-analysis

INTRODUCTION

Dietary fibers help to control energy intake and reduce the risk of developing obesity. Recent studies show that the consumption of polydextrose reduces energy intake at a subsequent meal. In this systematic review and meta-analysis we examine the subsequent effects of polydextrose on different levels of energy intake (EI).

METHOD

The review followed the PRISMA methodology. Meta-analyses were expressed as Standardized Mean Difference (SMD). A linear regression approach was used to model the relationship between the polydextrose dose and the different levels of EI expressed as a relative change (%).

RESULTS

All the studies included in this review administered polydextrose as part of a mid-morning snack. Six studies were included in the analysis of EI at an ad libitum lunch; and three were included in the analysis of EI during the rest of the day, as well as total daily EI. The meta-analysis showed that the consumption of polydextrose is associated with a reduction in EI at lunch time (SMD = 0.35; P <0.01; I(2) = 0). The dose of polydextrose consumed correlated significantly with this reduction in EI, EILunch (%) = -0.67 Polydextrose (g/day) (R(2) = 0.80; P <0.01). The meta-analysis of EI during the rest of the day and daily EI did not show any difference. Nevertheless, the regression equation indicates that there is a dose-dependent effect on the reduction of daily EI, EIDaily (%) = -0.35 × Polydextrose (g/day) (R(2) = 0.68; P <0.05). Sex-specific results are consistent with results for the whole group.

CONCLUSION

The studies included in this meta-analysis support the notion that the consumption of polydextrose reduces voluntary energy intake at a subsequent meal. Furthermore, this reduction in energy intake occurs in a dose-dependent manner.

Wheat bran extract alters colonic fermentation and microbial composition, but does not affect faecal water toxicity: a randomised controlled trial in healthy subjects

Wheat bran extract (WBE), containing arabinoxylan-oligosaccharides that are potential prebiotic substrates, has been shown to modify bacterial colonic fermentation in human subjects and to beneficially affect the development of colorectal cancer (CRC) in rats. However, it is unclear whether these changes in fermentation are able to reduce the risk of developing CRC in humans. The aim of the present study was to evaluate the effects of WBE on the markers of CRC risk in healthy volunteers, and to correlate these effects with colonic fermentation. A total of twenty healthy subjects were enrolled in a double-blind, cross-over, randomised, controlled trial in which the subjects ingested WBE (10 g/d) or placebo (maltodextrin, 10 g/d) for 3 weeks, separated by a 3-week washout period. At the end of each study period, colonic handling of NH3 was evaluated using the biomarker lactose[15N, 15N']ureide, colonic fermentation was characterised through a metabolomics approach, and the predominant microbial composition was analysed using denaturing gradient gel electrophoresis. As markers of CRC risk, faecal water genotoxicity was determined using the comet assay and faecal water cytotoxicity using a colorimetric cell viability assay. Intake of WBE induced a shift from urinary to faecal 15N excretion, indicating a stimulation of colonic bacterial activity and/or growth. Microbial analysis revealed a selective stimulation of Bifidobacterium adolescentis. In addition, WBE altered the colonic fermentation pattern and significantly reduced colonic protein fermentation compared with the run-in period. However, faecal water cytotoxicity and genotoxicity were not affected. Although intake of WBE clearly affected colonic fermentation and changed the composition of the microbiota, these changes were not associated with the changes in the markers of CRC risk.

Impact of dietary polydextrose fiber on the human gut metabolome

The aim of the present study was to elucidate the impact of polydextrose PDX an soluble fiber, on the human fecal metabolome by high-resolution nuclear magnetic resonance (NMR) spectroscopy-based metabolomics in a dietary intervention study (n = 12). Principal component analysis (PCA) revealed a strong effect of PDX consumption on the fecal metabolome, which could be mainly ascribed to the presence of undigested fiber and oligosaccharides formed from partial degradation of PDX. Our results demonstrate that NMR-based metabolomics is a useful technique for metabolite profiling of feces and for testing compliance to dietary fiber intake in such trials. In addition, novel associations between PDX and the levels of the fecal metabolites acetate and propionate could be identified. The establishment of a correlation between the fecal metabolome and levels of Bifidobacterium (R(2) = 0.66) and Bacteroides (R(2) = 0.46) demonstrates the potential of NMR-based metabolomics to elucidate metabolic activity of bacteria in the gut.

Effect of yogurt containing polydextrose, Lactobacillus acidophilus NCFM and Bifidobacterium lactis HN019: a randomized, double-blind, controlled study in chronic constipation

Background

Constipation is a frequent complaint and the combination of a prebiotic and probiotics could have a potentially synergic effect on the intestinal transit. The present study therefore aims to investigate the combination of polydextrose (Litesse®), L. acidophilus NCFM® and B. lactis HN019 in a yogurt on intestinal transit in subjects who suffer from constipation.

Methods

Patients with constipation were randomly divided into two groups, Control Group (CG) and Treatment Group (TG), and had to eat 180 ml of unflavored yogurt every morning for 14 days. Those in the CG received only yogurt, while the TG received yogurt containing polydextrose, L. acidophilus NCFM® (ATCC 700396) and B. lactis HN019 (AGAL NM97/09513).

Results

Favourable clinical response was assessed since Agachan score had a significant reduction at the end of the study in both groups and tended to be better in the TG. The subjects in the treatment group also had a shorter transit time at the end of the intervention compared to the control group (p = 0.01).

Conclusion

The product containing yogurt with polydextrose, B. lactis HN019 and L. acidophilus NCFM® significantly shortened colonic transit time after two weeks in the TG compared to CG and may be an option for treatment of constipation.

Different human gut models reveal the distinct fermentation patterns of Arabinoxylan versus inulin

Different in vitro models have been developed to assess how food compounds affect the human gut microbiota. Using two such models (SHIME(R) and TIM-2), we compared how long-chain arabinoxylan (LC-AX), a wheat-derived potentially prebiotic fiber, and inulin (IN), a well-established prebiotic compound, modulate SCFA production and bifidobacteria composition. While both the SHIME and TIM-2 differ in experimental design, they both demonstrated that LC-AX and IN specifically increased the health-promoting metabolites propionate and butyrate, respectively. Furthermore, LC-AX stimulated Bifidobacterium longum, while IN stimulated other bifidobacteria including Bifidobacterium adolescentis. The SHIME experiment also revealed that effects of LC-AX were more persistent during the 2-week wash-out period. These results confirm a recent in vivo study, during which humanized rats were treated with the same LC-AX/IN. In conclusion, results from different human gut models suggest that, besides IN, LC-AX are promising prebiotic candidates with high specificity toward Bifidobacterium longum and a selective propionate increase.

Polydextrose and soluble corn fiber increase five-day fecal wet weight in healthy men and women

Dietary fiber has well-established beneficial effects on laxation. Many fibers have been developed with positive sensory properties and 2 such fibers are polydextrose (PDX) and soluble corn fiber (SCF), which can be added to many commercially produced products. We conducted a randomized, double-blind, placebo-controlled, crossover study comparing the laxative effects of PDX and SCF at a dose of 20 g/d with a low fiber control (LFC) eaten daily as a muffin and cereal in 36 healthy men and women. Each treatment period was 10 d with a 2-wk washout period between. Participants collected fecal samples during the last 5 d of each treatment and completed food diaries and gastrointestinal tolerance questionnaires on d 1, 2, and 10 of each treatment period. Five-day fecal wet weight was higher after the PDX and SCF treatments than the LFC treatment (P ≤ 0.0007). The number of stools per day and daily fecal output also were significantly greater during the PDX treatment compared with the LFC treatment. The whole gut transit time did not differ among treatments. The PDX treatment resulted in a softer stool (P = 0.002) than the SCF and LFC treatments. Fecal pH was lowered by the PDX treatment (P = 0.02), whereas SCF tended to lower it compared with the LFC treatment (P = 0.07). When the participants consumed PDX and SCF, they reported significantly more flatulence and borborygmi compared with when they consumed the LFC. Consumption of PDX and SCF at a dose of 20 g/d results in a mild laxative effect with nominal gastrointestinal tolerance issues.

Digestive physiological outcomes related to polydextrose and soluble maize fibre consumption by healthy adult men

The objective of the present study was to evaluate digestive physiological outcomes elicited by functional fibres fed to healthy adult men. A total of twenty-one healthy adult men were utilised in a cross-over design. Each subject received polydextrose (PDX) or soluble maize fibre (SCF) (21 g/d) or no supplemental fibre (no fibre control; NFC) in a snack bar. Periods were 21 d and faeces were collected during the last 5 d of each period. Food intake, including fibre intake, did not differ among treatments. Flatulence (P = 0·001) and distention (P = 0·07) were greatest when subjects consumed PDX or SCF. Reflux was greater (P = 0·04) when subjects consumed SCF compared with NFC. All tolerance scores were low ( < 2·5), indicating only slight discomfort. Faecal ammonia, 4-methylphenol, indole and branched-chain fatty acid concentrations were decreased (P < 0·01) when subjects consumed the functional fibre sources compared with NFC. Faecal acetate, propionate and butyrate concentrations were lower (P < 0·05) when subjects consumed PDX compared with SCF and NFC. Faecal pH was lower (P = 0·01) when subjects consumed SCF compared with NFC, while PDX was intermediate. Faecal wet weight was greatest (P = 0·03) when subjects consumed SCF compared with NFC. Faecal dry weight tended to be greater (P = 0·07) when subjects consumed PDX compared with NFC. The functional fibres led to 1·4 and 0·9 g (PDX and SCF, respectively) increases in faecal dry mass per g supplemental fibre intake. Bifidobacterium spp. concentrations were greater (P < 0·05) when subjects consumed SCF compared with NFC. These functional fibres appear to be beneficial to gut health while leading to minimal gastrointestinal upset.

Dietary fiber type reflects physiological functionality: comparison of grain fiber, inulin, and polydextrose

Dietary fiber is a nutritional concept based not on physiological functions but on defined chemical and physical properties. Recent definitions of dietary fiber differentiate inherent plant cell wall-associated fiber from isolated or synthetic fiber. For the latter to be defined as fiber, beneficial physiological effects should be demonstrated, such as laxative effects, fermentability, attenuation of blood cholesterol levels, or postprandial glucose response. Grain fibers are a major natural source of dietary fiber worldwide, while inulin, a soluble indigestible fructose polymer isolated from chicory, and polydextrose, a synthetic indigestible glucose polymer, have more simple structures. Inulin and polydextrose show many of the same functionalities of grain fiber in the large intestine, in that they are fermentable, bifidogenic, and laxative. The reported effects on postprandial blood glucose and fasting cholesterol levels have been modest, but grain fibers also show variable effects. New biomarkers are needed to link the physiological functions of specific fibers with long-term health benefits.

Carbohydrates blended with polydextrose lower gas production and short-chain fatty acid production in an in vitro system

Maximizing health benefits of prebiotics, while limiting negative side effects, is of importance to the food industry. This study examined several oligosaccharides and their blends in an in vitro fermentation model. Substrates included medium- and long-chain fructooligosaccharides (FOS), oligofructose-enriched inulin, galactooligosaccharide, polydextrose (POL), and 50:50 substrate blends. Substrates and blends were fermented in vitro using human fecal inoculum, and fermentation characteristics were quantified at 0, 4, 8, and 12 hours. We hypothesized that mixtures of short- and long-chain oligosaccharides would generate less gas than do short-chain oligosaccharides and modulate gut microflora to a greater extent than do long-chain oligosaccharides. Carbohydrates blended with POL had decreased (P < .01) total gas volume and H(2) produced after 4, 8, and 12 hours of fermentation compared with individual carbohydrates. Mixing of 2 oligofructose-enriched inulin products led to less (P < .05) gas produced and a slower (P < .05) rate of production. When mixed with POL, all carbohydrates tested in the present study produced less total short-chain fatty acids (P < .04) and butyrate (P < .0001) after 12 hours of in vitro fermentation, compared with individual carbohydrates. The bifidogenic effect of medium-chain FOS and oligofructose-enriched inulin after 12 hours of in vitro fermentation was lower (P < .05) when mixed with POL. Mixing the pure carbohydrates with galactooligosaccharide increased (P < .05) bifidobacteria counts measured after 12 hours of in vitro fermentation, except when mixed with medium-chain FOS. In general, when mixed with POL, all carbohydrates had lower gas production, gas production rates, butyrate and total short-chain fatty acid production, and bifidobacteria counts than when fermented alone for 12 hours.

Effect of different prebiotics on the fermentation kinetics, probiotic survival and fatty acids profiles in nonfat symbiotic fermented milk

The simultaneous effects of different binary co-cultures of Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus rhamnosus and Bifidobacterium lactis with Streptococcus thermophilus and of different prebiotics on the production of fermented milk were investigated in this paper. In particular, we determined and compared the kinetics of acidification of milk either as such or supplemented with 4% (w/w) maltodextrin, oligofructose and polydextrose, as well as the probiotic survival, chemical composition (pH, lactose, lactic acid and protein contents), fatty acids profile and conjugate linoleic acid (CLA) content of fermented milk after storage at 4 degrees C for 24 h. Fermented milk quality was strongly influenced both by the co-culture composition and the selected prebiotic. Depending on the co-culture, prebiotic addition to milk influenced to different extent kinetic acidification parameters. All probiotic counts were stimulated by oligofructose and polydextrose, and among these B. lactis always exhibited the highest counts in all supplemented milk samples. Polydextrose addition led to the highest post-acidification. Although the contents of the main fatty acids were only barely influenced, the highest amounts of conjugated linoleic acid (38% higher than in the control) were found in milk fermented by S. thermophilus-L. acidophilus co-culture and supplemented with maltodextrin.

Ingestion of the soluble dietary fibre, polydextrose, increases calcium absorption and bone mineralization in normal and total-gastrectomized rats

We previously demonstrated that feeding a highly fermentable and water-soluble dietary fibre, guar-gum hydrolysate (GGH) increased intestinal absorption of insoluble Ca salts in total-gastrectomized rats. In the present study, we examined the effects of feeding a less fermentable and water-soluble fibre, polydextrose (PD), on Ca absorption and bone mineralization in the normal and total-gastrectomized rats in comparison with the effects of GGH. Apparent Ca absorption was severely lowered by gastrectomy, and PD feeding (50 g/kg diet) partially restored the reduction of Ca absorption similarly to GGH feeding (50 g/kg diet). PD feeding also increased the Ca absorption in normal rats, but not GGH feeding. Femur Ca concentration was reduced with gastrectomy. Feeding PD for 21 d increased the bone Ca concentration in both normal and gastrectomized rats, but GGH feeding did not. In rats fed PD, pH of the caecal contents was lower than in rats fed fibre-free and GGH diets; however, soluble Ca concentration in the caecal contents was not different between the diet groups. Short-chain fatty acid concentrations were much lower in the PD groups than in the GGH groups. We also examinedin vitroCa absorption by using everted sacs of the small intestine. Addition of PD to the serosal medium of the ileal sacs increased Ca absorption, but addition of GGH did not. These results suggest that the small intestine rather than the large intestine is responsible for the increase in Ca absorption in rats fed PD, and suggests that the mechanism for the increase by PD may be different from that by GGH.

Faecal bacterial mass and energetic losses in healthy humans and patients with a short bowel syndrome

OBJECTIVE

In addition to non-digested nutrients, human stools contain endogenous substrates, among which bacteria are a major component, whose growth may be stimulated when more dietary nutrients are available for bacterial fermentation, as in patients with malabsorption syndrome. We assessed the energy content and composition of both stools and faecal bacteria in healthy volunteers and patients with a short bowel and colon in continuity (SBC). Our goal was to clarify the magnitude of error introduced by the faecal bacteria in the measurement of the digestibility of ingested energy and nutrients.

SUBJECTS AND METHODS

We studied six healthy volunteers and six patients with a SBC under free oral intake. The bacterial mass of stools was isolated. In the bacterial fractions and fresh stools, calorie, fat, nitrogen and short-chain fatty acid contents were determined. The Wilcoxon signed rank or the Mann-Whitney tests were used for comparison.

RESULTS

In healthy volunteers and patients with SBC, faecal bacterial mass accounted for 44 and 35% of faecal dry weight, and contained 50 and 34% of total faecal energy. In healthy volunteers, the apparent digestibilities when corrected by bacterial constituents (88-97% according to nutrients) were significantly higher than the apparent non-corrected digestibilities (84-94%). In patients with SBC, the corrected apparent digestibilities (69-89% according to nutrients) were significantly higher than the apparent non-corrected digestibilities (54-83%).

CONCLUSION

The error introduced by the faecal bacterial fraction when assessing the extent of nutrient digestibility is small in healthy volunteers; it is more pronounced in patients with SBC, reaching 18% for the digestibility of ingested fat.

Polydextrose, lactitol, and fructo-oligosaccharide fermentation by colonic bacteria in a three-stage continuous culture system

In vitro fermentations were carried out by using a model of the human colon to simulate microbial activities of lower gut bacteria. Bacterial populations (and their metabolic products) were evaluated under the effects of various fermentable substrates. Carbohydrates tested were polydextrose, lactitol, and fructo-oligosaccharide (FOS). Bacterial groups of interest were evaluated by fluorescence in situ hybridization as well as by species-specific PCR to determine bifidobacterial species and percent-G+C profiling of the bacterial communities present. Short-chain fatty acids (SCFA) produced during the fermentations were also evaluated. Polydextrose had a stimulatory effect upon colonic bifidobacteria at concentrations of 1 and 2% (using a single and pooled human fecal inoculum, respectively). The bifidogenic effect was sustained throughout all three vessels of the in vitro system (P = 0.01 seen in vessel 3), as corroborated by the bacterial community profile revealed by %G+C analysis. This substrate supported a wide variety of bifidobacteria and was the only substrate where Bifidobacterium infantis was detected. The fermentation of lactitol had a deleterious effect on both bifidobacterial and bacteroides populations (P = 0.01) and decreased total cell numbers. SCFA production was stimulated, however, particularly butyrate (beneficial for host colonocytes). FOS also had a stimulatory effect upon bifidobacterial and lactobacilli populations that used a single inoculum (P = 0.01 for all vessels) as well as a bifidogenic effect in vessels 2 and 3 (P = 0.01) when a pooled inoculum was used. A decrease in bifidobacteria throughout the model was reflected in the percent-G+C profiles.

A review of the clinical toleration studies of polydextrose in food

Polydextrose is a non-digestible 1 kcal/g polysaccharide used primarily as a sugar replacer and dietary fiber in foods. At typical use levels, polydextrose provides physiological effects similar to those of other dietary fibers. However, excessive consumption of non-digestible carbohydrates can lead to gastrointestinal distress. Nine clinical studies were conducted with polydextrose to evaluate the extent of such symptoms. These studies determined laxation endpoints in adults and children, and showed that polydextrose was better tolerated than most other low digestible carbohydrates (e.g. polyols). This is because of a higher molecular weight and partial colonic fermentation, leading to a lower risk of osmotic diarrhea. After evaluating these studies, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) and the European Commission Scientific Committee for Food (EC/SCF) concluded that polydextrose has a mean laxative threshold of approximately 90 g/d (1.3 g/kg bw) or 50 g as a single dose.

Studies on the effects of polydextrose intake on physiologic functions in Chinese people

BACKGROUND

Previous studies showed that polydextrose has physiologic effects similar to those of dietary fiber.

OBJECTIVE

Ingestion of 4, 8, and 12 g polydextrose/d was studied to determine the physiologic effects in Chinese subjects.

DESIGN

In a placebo-controlled, randomized, double-blind study, we evaluated the effects of polydextrose ingestion on clinical biochemistry indexes, glycated hemoglobin, glucose tolerance, the glycemic index, bowel function, stool weight and pH, short-chain fatty acid production, fecal microflora, and cecal mucosa cell proliferation.

RESULTS

Polydextrose had no significant effect on blood biochemistry indexes. Ingestion of 12 g polydextrose plus 50 g glucose resulted in a glycemic index of 89% (compared with a glycemic index of 100% after ingestion of 50 g glucose). Bowel function (frequency and ease of defecation) improved significantly and there were no reports of abdominal distention, abdominal cramps, diarrhea, or hypoglycemia. Fecal weight (wet and dry) increased and fecal pH decreased proportionally to polydextrose intake. Short-chain fatty acid production-notably that of butyrate, isobutyrate, and acetate-increased with polydextrose ingestion. There were substantial changes in fecal anaerobes after polydextrose intake. BACTEROIDES: species (B. fragilis, B. vulgatus, and B. intermedius) decreased, whereas LACTOBACILLUS: and BIFIDOBACTERIUM: species increased. The cecal mucosa whole-crypt labeling index increased, with colonocyte proliferation mainly occurring in base compartments, which provided an indirect confirmation of butyrate production in the colon.

CONCLUSION

Polydextrose ingestion had significant dietary fiber-like effects with no laxative problems.

Digestion and physiological properties of resistant starch in the human large bowel

The digestion of four sources of resistant starch (RS) has been studied in twelve healthy volunteers who ate controlled diets for 15 d periods. RS from potato, banana, wheat and maize (17-30 g/d) was compared with a starch-free diet, a diet containing wheat starch that was fully digested in the small intestine, and with 18.4 g NSP from brand/d. RS increased stool wet weight by 1.6 g/d per g RS fed for potato, 1.7 for banana, 2.5 for wheat and 2.7 for maize, but this was significantly less than bran NSP at 4.9 g/g. RS was extensively digested in twenty-seven of thirty-four diet periods but five subjects were unable to break down one or two of the RS sources. Faecal N and energy excretion were increased. RS decreased NSP breakdown and RS2 (resistant starch granules) tended to prolong transit time. All forms of RS increased faecal total short-chain fatty acid excretion. RS2 (from potato and banana) gave greater proportions of acetate in faeces, and RS3 (retrograded starch from wheat and maize) more propionate. We have concluded that RS2 and RS3 are broken down in the human gut, probably in the colon although in 26% of cases this breakdown was impaired. RS exerts mild laxative properties, predominantly through stimulation of biomass excretion but also through some sparing of NSP breakdown.